''There is a possibility of a destructive regional tsunami in the Indian Ocean,'' the agency said in a statement, adding that the Indian Ocean coasts of Sumatra and Java and Australia's Cocos Islands could be affected within an hour.

It said all coasts of India's Andaman and Nicobar Islands and all coasts of Sri Lanka could be affected between one to three hours.

The US Geological Survey (USGS) said the quake, which came about 14 hours after another powerful tremor in the same area, measured 7.5. It had earlier put its strength at 7.9.